Electrical lamp socket



Jan. 13, 1959 s, UART 2,869,097

ELECTRICAL LAMP SOCKET Filed July 3, 1957 SIMON STUART BY FIQB j K.

ATTORNEY ELECTRICAL LAMP SOCKET Simon Stuart, Bronx, N. Y. Application July 3, 1957, Serial No. 669,896

4 Claims. (Cl. 339-69) This invention relates to lamp sockets and, more particularly, to a novel lamp socket adapted for quick relatively permanent attachment to a lamp cord and to quick insertion of a lamp bulb therein.

In assembling lamp sets, such as used in Christmas tree ornamentation for example, it is necessary to electrically connect each of a plurality of lamp sockets to a lamp cord and then to screw a bulb into each socket.

The electrical connection of each socket to the supply cord has hitherto involved soldering of leads to terminals or securing of the conductors to screw type pressure terminals. The time and labor required for such operations, as well as the time and labor required to screw a lamp bulb into each socket, has made the cost of such lamp sets unduly high.

For example, the usual lamp socket for such lamp sets comprises a socket of dielectric material in which is secured a cylindrical threaded member of conductive metal forming the side contact for the base of the lamp United States atent O bulb. This side contact is usually secured in place by a metal rivet or screw to which one conductor of the cord is electrically connected. The socket also includes a center or base contact, of the spring type, which is also screwed or riveted in place and electrically connected to the other conductor of the cord. Thus, even the assembly of such a socket requires substantial time and labor.

In accordance with the present invention, a novel lamp socket is provided in which no soldered, riveted, or threaded connections are needed, and into which a lamp bulb can be easily inserted by merely pressing it into the socket without any screwing in operation, although the lamp bulb, when inserted into the lamp socket, can be removed only by a screwing out operation.

More specifically, the socket comprises a cylindrical body formed of a suitable dielectric material such as a synthetic resin. A rigid thermosetting plastic material is preferred. This body has a base or partition located somewhat inwardly of one end and formed with a pair of diametrically opposite substantially rectangular openings which may align with grooves along the inner surface of the cylindrical wall. The base further has a pair of diametrically opposite arcuate slots or openings each intermediate the rectangular openings. A supply cord slot extends diametrically of the outer surface of the base between the rectangular openings, this slot opening outwardly of the body at each end.

The rectangular slots receive the socket terminals which are relatively elongated strips of electrically conductive metal insertible through the rectangular slots into the socket. Each terminal has a cross member adjacent its lower end limiting its movement into the socket, and the lower end of each terminal is formed with conductor piercing and electrical contact making barbs. When the two terminals are in place, the barbed ends of the respective terminals are staggered laterally of the supply cord slot so that each terminal makes electric contact with a different conductor of the supply cord.

One of the terminals constitutes the side terminal or contact for the lamp base, and is formed with an inwardly reentrant hook on its free or outer end and with trans verse undulations inwardly of the hooked end. When the side terminal is in place, its undulating portion is bowed away from the socket wall. The other, or base terminal, has an outer end bent to extend radially of the socket when this terminal is in position.

To assemble the socket, the respective terminals are inserted through the base of the body and a supply cord is laid in the diametric slot in the base with its conductors pressed onto the respective barbed ends of the terminals. A cap of flexible material is then snapped into interlocking relation with the body to force the conductors firmly onto the barbs.

This cap is formed of dielectric material, preferably a fire retardant thermoplastic and thus flexible material. The cap comprises a circular end wall from which projects a pair of diametrically opposite arcuate cross-section extensions engageable through the arcuate slots of the base by virtue of their flexibility. Each extension has a rib on the inner surface of its free end, and the relative proportion of parts is such that, when these ribs snap into engagement with the inner surface of the base due to the flexibility of the cap, the cap wall engages the bottom of the socket body and firmly presses the conductors onto the-barbs. The flexibility of the cap allows permanent assembly of the socket without the use of rivets, screws, or other fasteners.

When the socket is of the type used in Christmas tree lamp sets, a tree branch engaging clip may have a hooked end inserted in an opening in the socket body and locked in place by the cap.

For an understanding of the invention principles, reference is made to the following description of a typical embodiment thereof as illustrated in the accompanying drawing. In the drawing:

Figs. 1 and 2 are axial sectional views of the socket taken at right angles to each other;

Fig. 3 is a partial axial sectional view of the socket with a lamp therein;

Fig. 4 is a bottom plan view of the socket body;

Figs. 5 and 6 are, respectively, front and side elevation views of the bulb retaining contact element; and

Figs. 7 and 8 are, respectively, front and side elevation views of the bottom contact element.

Referring to the drawing, the lamp socket forming the subject matter of the invention comprises a socket body 10, a socket cap 20, a bulb-retair1ing and conductor piercing side contact 25 and a bottom conductor piercing contact 30. Body 10 and cap 20 are molded from a suitable dielectric material, the body 10 being formed of a rigid thermosetting plastic material and the cap 20 being a fire retardant thermoplastic material such as cellulose acetate for example. Contacts 25 and 30 are stampings of electrically conductive metal such as brass, copper, or aluminum.

Body 10 is a generally cylindrical member having a substantially closed inner end 11 and an open outer end. End 11 has a conductor receiving slot or groove 12 extending thereacross and communicating adjacent each end with substantially rectangular opening 13 aligned with diametrically opposite grooves 14 extending longitudinally of the inner surface the side wall of member 10. The inner end of each groove 14 is recessed or notched as at 15.

The segmental ribs 16 formed by groove 12 have arcuate openings 17 therein for a purpose to be described, and these openings have recesses or notches 18 adjacent radial openings 19.

Cap 20 is generally annular and formed with a circumferential rib 21 at its inner end. The cap has diametrically opposite arcuate extensions 22 on its inner end each having an inturned lip 23 at its free end. These extensions fit 'through'openings 17-"when the--socket -is assembled. v

Side contact 25 is an enlongated strip having a crosshead 26 atone end, "ahook 27 "at theother-end,-"'and undulations 28 in-a bowed intermediate section29adjacent hook 27. 'Conductor piercing prongs 24-project from the side' of head 26' adjacent' one end.

'- *End contact 30 is also an "el-ongatedstr iphaving a cross he'ad'31 andastem'32 extending at' an a'ngle thereto.

Conductor piercing-prongs 33 project'from the edge'of head 31 adjacent one-end.

*In assembling the-socket, contact 25 isinsertedthrough one opening 13 to-extend along the associated groove 14 withbowed "section 29" projecting "from" the "groove.

Head "26limits inwardmovement of-contact 25. Conta'ct"30 is inserted in'the' other opening 13 so that stem 32 extends across the centerof thesocket. When the contacts-are thus"inserted,'prongs 24'lie on one side of -tl1e centerlineof groove 12-and cntacts 33 lie onthe other side of such centerline.

A- two-conductor cord, or two single insulated stranded the inner surface of end -Wall-11'. *Thisrcloses groove 12 a'ncl forces th'e-wires '34 firmly onto the -prongs 24 and 33.

- 1 A lamp "bulb 40 is easily and quickly assembled with the socketiby rnerely' pushing itsthreaded base 41 into the socket until the center base contact engages and depresses-stern 32 of-contact 30'. Bowed portion 29 off-contact 25 gi'ves' toallow base '4 l"t'o slip"pa'st. -=Hewever, to re'move bulb 40, it "must "be unscrewed from the socket as hook end 27 prevents pulling-fthe bulb out. This -hook is' -canted insuch a-direction that upward stress on the hookcauses bowed section 29 to grip the lamp: base even more firmly.

Bulb 40 may also be screwed into the socket as well as pushedin-axially.' The resilieney of bowed portion 29 of contact 25 permits the 'threads of base 41 to'slip over undulations 28 if it i's attempted'to screw bulb '40 into the rsocket=beyond the point at which the center contact of base 41 engages contact '30. Thus, if it is attempted to tighten bulb 50" by grasping the ibulb'and turning it further into the socket; there is no possibility of twi'stingthe-bulb otl its -base,'-due to the very small resistancerto turning movement of the bulbas the base I threads slip over i undulations r 28.

. LT-heflexibility of the ntat'erialof capZWa-ll'ows fingers 22 1 with=ribs -23to deflect-as the fingers are inserted through; openings '17 and then'sn'ap back to engage ribs 23 .over the -inner surface o-f wall 11 to lock the parts together permanently!- Thereby, nobolts,screws,'rivets or other fasteners are needed to'secure the*socl et---parts v:together.

1 :Whilelaispecific embodiment oflthe invention ih'asibeen i shown .and*desc'ribed in J-de'taiPto' illustrate the application of the" invention A principles, itwill be *understood that the invention'may be embodied'otherwise withoutdepart- .ingfrom such principles.

What is claimed is:

1. "A lamp socket comprising, in combination,--asubstantially cylindrical socket body having a base formed with a pair of substantially diametricallyfopposite apertures communicating with grooves extending along the inner surface of said socket, and formed with a groove extending diametrically of its undersurface and communicating with said apertures; 21 first contact in the form of a., r.elatively elongated metal strip having an enlarged .head formed with insulation piercing barbs, said first contact extending upwardly through one of said apertures with its head in said base groove and limiting upward movement of said first contact 'said 'first contact extending diametrically of ,said.,base and spaced from the upper surface thereof to engage the center contact of a threaded lamp base; a second contact adapted to engage the side contact of the threaded lamp base and including a relatively narrow second strip of conductive metal --ex='tending through the other aperture "and longitudinally of one of the grooves -in-the inner -'surface -of--the cylindrical wall ofsaid -socket-'*body,said second strip having transverse undulations intermediate=its ends engageable with the threads of the lamp base and'the undnl'ated-portion of said--second stripbeing bowed inwardly from said W311," and havingan enlarged head in saidbase groove limiting-upward ntovement of said second contact and'forme'd with conductor piercing barbs; whereby a t lamp bulb may be -mounted in said socket "by non-rotational movement axially -into*said-socke t'to i flatten'said second strip toward-said Wa'll',--'said-second l'strip having aradially and axially inwardly directedhook on its outerend =engageable-"withthe threads of-the lamp base to prevent removal of. the lamp -bulbfromsaid "socketexcept by an unscrewing rotation'of the lamp of said groove to engage different conductors of -atwo- Lconductor cable in' saidbasegroove; saidcbasehaving a -fipair of diamet'rica'lly; opposite arcuate openings interimediat'e said-aperturesr andiasocket *cap--having1acirci1l ar wall and apa'ir of diametrically opposite arcua-tecross- 2 section fingers extending --longitudinally from said wall forzinsertion through said arcuate openings; the free ends of said fingers having ribs on-the-innersurfacestheredf engageable with the upper-surface 'ofthe socket base; the distance of said ribs-from-saidcap Wall *being such that, when said ribs are engaged over the'upper surface of Sald =SOCl 6t'baS, said cap wall'will firmly "press the conductors of'such cord in sa-id groove onto said barbs.

'2. A lamp socket as. claimed in claim lin which said socket-body has a side opening therein; and a socket mounting clip having an endengaged in said side opening and retained in position by said cap.

3. A lamp-socket as claimedin-claim'l, in whichsaid cap is formed of thermoplastic material. 4. rA- lamp socket as-claimed in; claim 1 in :whi'chjsaid Y socket base is formed -of"athermosetting materialj and i said capis formed ofa thermoplastic-material.

References Citedgin the file of this-patent UNITEDSTATES PATENTS 

